Advances in networking and transmission of digital multimedia data has provided users with a huge number of information catalogues, such as music catalogues. These advances thus raise not only the problem of distribution, but also the problem of choosing desired information among huge catalogues.
Such new developments raise music selection problems which may depend on the aims of users or content providers. Although modelling a user's goal in accessing music is very complex, two basic elements, i.e. desire of repetition and desire of variation or surprise, can be identified.
The desire of repetition means that people want to listen to music they already know, or similar to what they already know. Sequences of repeating notes create expectations of the same notes to occur. On the other hand, the desire for variation or surprise is a key to understanding music at all levels of perception.
Of course, these two desires are contradictory, and the issue in music selection is precisely to find the right compromise: provide users with items they already know, or items they do not know but would probably like.
From the viewpoint of record companies, the goal of music delivery is to achieve a better exploitation of the catalogue. Indeed, record companies have problems with the exploitation of their catalogues using standard distribution schemes. For technical reasons, only a small part of a catalogue is actually “active”, i.e. proposed to users, in the form of easily available products. More importantly, the analysis of music sales shows clearly decreases in the sales of albums, and short-term policies based on selling many copies of a limited number of items (hits) are no longer efficient. Additionally, the sales of general-purpose “samplers” (e.g. “Best of love songs”) are no longer profitable, because users already have the hits, and do not want to buy CDs in which they like only a fraction of the titles. Instead of proposing a small number of hits to a large audience, a natural solution is to increase diversity, by proposing more customised albums to users.
In the present invention, the term “database” is used for designating any collection of data, e.g. covering both pre-stored data and dynamically stored data. The term “metabase” is used to describe a database containing descriptors of the items in the database. There are many situations in which it is necessary or desirable to create a sequence of items (e.g. music titles) from a collection of items for which data are available. It is also important that a created sequence is “coherent”, i.e. there should exist a particular relationship between descriptors of the items which constitute a sequence. Typically, the descriptors of the items, components of the sequence, should not be too dissimilar, especially for successive items in the same sequence. A typical case where the problem supra arises is in the field of multimedia. A notable problem concerns an automatic generation of music programs, the latter being an example of temporal sequence. Here the term “program” is used not only to designate a sequence of musical pieces, but also, more generally, any temporal sequence of multimedia items, e.g. film clips, documentaries, texts.
A system producing “coherent” sequences of items in a particular order is disclosed in European patent application EP-A-0 961 209.
The items descriptors are stored in a metabase and consist of data pairs respectively consisting of a descriptor and a corresponding value. The problem of creating the desired sequence is treated as a “Constraint Satisfaction Programming (CSP)”, also disclosed in the European patent application supra. The sequence to be obtained is specified by formulating a collection of constraints holding on items in the metabase. Each constraint describes a particular property of the sequence, and the sequence can be specified by any number of constraints.
The items in the metabase exhibit a particular generic format with associated taxonomies for at least some of the descriptors. Also, the constraints are specified out of a predetermined library of generic constraint classes which have been specially formulated. The special constraint classes allow the expression of desired properties of the target sequence, notably properties of similarity between groups of items, properties of dissimilarity and properties of cardinality. These constraint classes enable the properties of coherent sequences to be expressed in a particularly simple manner.
It is the combination of the use of a generic format for items in the data base and the special constraint classes which enables the use of a CSP solution technique to solve the combinatorial problem of building an ordered collection of elements satisfying a number of constraints.